1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus.
An electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming process. Examples of electrophotographic image forming apparatus include an electrophotographic copier, an electrophotographic printer (an LED printer, a laser beam printer or the like), an electrophotographic facsimile device, an electrophotographic word processor, and the like.
2. Related Background Art
In an electrophotographic image forming apparatus using an electrophotographic image forming process, a process cartridge system has been conventionally adopted in which an electrophotographic photosensitive drum and process means, which acts on the electrophotographic photosensitive drum, are integrally formed as a cartridge and the cartridge is detachably mountable to a main body of an electrophotographic image forming apparatus. According to the process cartridge system, maintenance of the apparatus can be performed by not a service man but a user himself and the operability can be significantly improved. Thus, the process cartridge system has been widely used in the electrophotographic image forming apparatus.
Further, a cartridge configuration, in which the respective process means are formed as a cartridge has been realized. For example, a developing cartridge in which a toner containing portion and developing means are integrally formed, or a process cartridge, in which an electrophotographic photosensitive member, charging means and cleaning means are integrally formed or the like, has been adopted.
The demand for a color electrophotographic image forming apparatus capable of forming a color image has recently increased, Thus, the introduction of a color electrophotographic image forming apparatus which can attain the following six objectives is expected:
(1) a low running cost; PA1 (2) a compact size; PA1 (3) low power consumption; PA1 (4) high-quality image production; PA1 (5) a high speed; and PA1 (6) improved operability.
In these demands, for example, as a countermeasure for the item (1) a low running cost, a further increase in the life of the above-mentioned process means can be considered.
However, the amount of toner corresponding to the life of process means becomes an amount proportional to the life of the process means. For example, in a case where the life of process means is 50000 sheets of images, an amount of toner needed reaches 1.25 to 1.5 kg. When such a large amount of toner is integrally contained in a cartridge, the total weight and volume of the cartridge significantly become large and an operability may be lowered.
Further, since the space occupied by the entire cartridge is increased, miniaturization (downsizing) of the entire apparatus may become difficult. Further, a frame for supporting a cartridge with a large weight with high precision is needed and the total cost may increase.
The present invention has further advanced the above-mentioned conventional arts.